The ability of capturing metals and/or radionuclides from large amounts of water is important for radioisotope waste treatment and environmental cleanup. We have developed an approach that rapidly optimizes the capturing of radioisotopes in large-volume aqueous environments. The approach was scaled up to capture beryllium-7 from 300 gallons of cooling water associated with a linear accelerator. Solid supports with the functional groups sulfonic acid, iminodiacetate, pyridine amine, pyridine amine acid, or quaternary amine were incubated in the cooling water for 1 week. One sulfonic acid solid support was able to capture 2.1 mCi of Be-7. Subsequent studies with the sulfonic acid solid support focused on the uptake over time of Be-7, scale-up of capturing Be-7, and subsequent purification of Be-7. The uptake over time of Be-7 was found to be linear in the first 24 h, with an equation of Y = 4.11X (% uptake/time (h)) (R 2 = 0.998). The uptake of Be-7 reached the maximum at 24 h and was identical to the uptake at 168 h. To purify Be-7, the optimal purification approach was to release the Be-7 from the solid support with 10 M HCl, which could be immediately passed through an AG1 resin to remove radioimpurities. The radiopurity of the purified Be-7 was greater than 99%, and this method was used to purify 65 mCi of the isotope.